Reformatting an SD card with a different file system, or even with the same one, may make the card slower, or shorten its lifespan. Some cards use wear leveling, in which frequently modified blocks are mapped to different portions of memory at different times, and some wear-leveling algorithms are designed for the access patterns typical of FAT12, FAT16 or FAT32. In addition, the preformatted file system may use a cluster size that matches the erase region of the physical memory on the card; reformatting may change the cluster size and make writes less efficient. Data on SD card are not fully erased during every high-level format.

Instead, the area on the SD card containing the data is merely marked as available, and retains the old data until it is overwritten. If the SD card is formatted with a different file system than the one which previously existed on the partition, some data may be overwritten that wouldn’t be if the same file system had been used. However, under some file systems (e.g., NTFS, but not FAT), the file indexes (such as $MFTs under NTFS, inodes under ext2/3, etc.) may not be written to the same exact locations. And if the partition size is increased, even FAT file systems will overwrite more data at the beginning of that new partition.

Sandisk sd card used by smart phones, digital cameras and so on. But also to other smart phones and other products manufacturers supply.

“Full Scan” to recover data from Sandisk sd card corrupted if partitions show as “raw” or recover deleted data files which cannot be found with “undelete” and “unformatted” and “recover partition”, recover data files from raw partition, recover data files of partitions which are not NTFS, nor exfat, or fat3, after showing an error, display as raw file system, unformatted, unknown partition, unpartitioned, needs to be formatted.